Blasting cartridge shell



March 2, 1943. c BARKER BLASTING CARTRIDGE SHELL Filed Nov. 22, 1939INVENTOR v C'ZAUDE L. 645mm Patented Mar. 2, 1943 1 2,3123% BLAST-INGCARTREGE SH Claude L. Barker, Denver, 0010., 'assignor to E. I.

du Pont de Nemours & Company, Wilmington, Del., a corporation DelawareApplication November 22, 1939, Serial No. 305,631

1 Claim.

This invention relates to an improved explosive cartridge for use inblasting operations, and more particularly to a modification im the formof the wrapper about said cartridge whereby increased effectiveness isrealized- Dynamite cartridges commonly comprise pre- (Cl. roe-24) formedcylindrical paper shells which have been the packages arerelativelyrigidin nature and,

deformable only with difiiculty. Various diam- The object of myinvention is an improved explosive package that overcomes thedificulties heretofore encountered. A further object is an explosivecartridge which is readily conformable to the shape and size of theborehole by means of ordinary tamping procedures. A further object issuch a cartridge which becomes readily wedged into a borehole and fillsit completely is an explosive cartridge contained in a wrap-' eters areused for such cartridges, 2. common size being 1 inches in diameter by 8inches in length.

In blasting it is customary to drill a borehole into the rock, thediameter of the hole depending on the diameter of the dynamite cartridgeto be inserted. The cartridges are loaded to the desired depth in thehole, each one ordinarily being tamped or rammed tightly into positionwith a long rod. It frequently happens that the boreholes containirregular portjons which are larger in diameter than the cartridges tobe inserted. It would be desirable to rupture the dynamite wrapper andallow the explosive to fill the hole completely under the effect ofvigorous tamping, thus enhancing the blasting execution. The rigidity ofthe filled cartridge, however, makes such rupture very difilcult, evenimpossible, in many cases. Trouble from the same cause is likewise metin loading pulverulent high explogravity. Difliculties of the abovenature have without the necessity of any preliminary treatment at theplace of use. A still further object per of such construction as tobring about the advantages cited. Additional objects will be described.as the invention is disclosed further hereinafter.

I have found that the foregoing objects are attained and the obstaclesof prior practice overi come by enclosing the explosive in a shell ofrupturable material having rows of perforationsor other weakeningindentations in rectilinear arrangement. It is essential that the row ofperforations be disposed in a spiral around the sides of the finishedshell so that the row makes an acute angle with the axis of said shell.In one embodiment, the perforations in'the paper are so placed that inthe rolled cartridges the rows of perforations are superposed on oneanother. In another embodiment, the rows are offset in the rolledcartridge. Such an explosive package presents a rigid appearance anddoes not become distorted in handling. When charged into av I borehole,however,brealring of the paper wrapbeen met by the procedure of slittingthe cartridges with a knife so that the explosive material can readilyexpand and conform to the size and shape of the borehole. Theslittingoperaallel sides.

per along the lines of the rows of perforations presents no difflcultiesand the explosive takes the form of the borehole and fills itcompletely.

In order'that the shape of the shell paper and the arrangement of theperforations may be seen more clearly, Figure 1 shows a sheet of paperof trapezoidal form adapted to serve as the wrapper for explosivecartridges. Figure 2 shows a similar paper sheet in the form of aparallelogram. Figure 3 is a view of a completed cylindrical explosivepackage accordingto the present inventionT Referring to Figure l, thesize of the sheet ABCD' will depend on the diameter of the cartridgeintended. Assuming a 1%" x 8"- cartridge, suitable dimensions willcomprise lengths 017%" and 11% for the parallel sides and 10" for theperpendicular distance between said parsisting of small circularopenings resembling pin holes are made in the shell paper alongthestraight lines GI, FJ, and KL, these rows stop: Pmsabtmt 1" from theedge of the paper sheet Parallel-rows of perforations conalong theparallel sides but extending to the very edge wherever they meet thenon-parallel sides. The slope of the rows of perforations is such as toform approximately a 50 angle with the base and top of the sheet. Theexplosive container is prepared by forming the paper ABCD into acylinder about a rotating mandrel, with the end of the mandrel extendingto the line GH. The protruding portion is then bent inwardly at aplurality of places and so pressed that a stiff crimp is formed. It isnot necessary to the invention that the rows of perforations besuperposed on one another in the rolled cartridge. However, thisarrangement may be employed, if desired. If such a structure iscOntemplated the rows are separated along the lines EF and GH by adistance substantially equivalent to the circumference of the cartridge,that is by about 3.9" in a cartridge of 1%." diameter. In the embodimentin which no exposed perforations appear on the wrapped cartridge, it isim-.

portant that I be removed from E by a distance at least as great as thecircumference. The above cylindrical container is filled with explosivematerial to the level EF, and the cartridge is closed tightly bycrimping over the portion Figure 2 is similar to Figure 1 except that itshows a paper sheet of the shape of a parallelogram, namely, MNOP.Intended for a 1 x 8" cartridge. again, suitable dimensions will be aheight of a length of top and bottom sides of 9", and a base angle ofaround 70. Rows of perforations are made in the shell paper, the rowsagain starting at points about. 1" from the top and bottom parallelsides of the sheet but v extending to the edge of the sheet onthe sidesMP and 0N. These rows, sU, VW, and Y are parallel to one another and areseparated by a distance equal to the circumference of the wrappedcartridge, approximately 3.9" for a 1%," diameter cartridge. are slopedso that the acute angle with the top and bottom parallel sides isapproximately 50.

' vIf it is intended that no perforations are-to be exposed on thewrapped package, the top of the first row of perforations is separatedfrom the edge of the sheet by a distance QU, at least as great asthe-circumference of the cylindrical cartridge. -The cylindricalcontainer for the explosive is prepared. as in Figure 1, by rollingabout a mandrel and crimping. The cartridge, filled to the level QR, isclosed tightly by folding over the emergent paper. I

In" Figure 3, the completed perforations GI are depicted on the finishedcylindrical explosive package orcartridge.

The. rows of perforations" I particularly to paper shells, but it willbe under- In the foregoing specific embodiments of cartridges formedfrom papers weakened in accordance with the invention, three rows ofperforations have beenshown. In many cases, two rows may be sufilcientand ,the outer rows GI and SU of Figures 1 and 2,-re'spectively, may beomitted.

In all events, however, I prefer to have more than one row of suchperforations in the shell paper blank. -While I have applied theembodiments to shell papers for.1 diameter car- T tridges, it will beapparent that the invention is applicable to all diameters, 1 2'! etc.,and even unto the vary large diameters. The illustrations have shown theperforations stopping at a distance from the top and bottom sides of thepaper substantially equal to the amount crimped over. In a cartridge of1%" diameter,

this distance may be approximately 1", while vention is applicable tocartridges containing all types of explosive whether pulverulent, gelatiin the 2" cartridge diameter, it may be about 1 In general, the largerthe diameter, the greater the width of paper utilized in crimping. It isundesirable from the point of view of tightness of cartridge that theperforations come completely to the edges of AB and CD.

pendicular to the longitudinal axis of the wrapped package. I have foundthat the acute angle of the rows of perforations with said parallelsides should be within the range of 35 to 70, and: preferably between 45and 55, for instance about 50. That is, the row of perforations ofthe'flnished cartridge will make an acute angle of 20 to 55 with theaxisbf said cartridge. Such an angle assures greater ease in rupturingthe shell by the tamping operation and assures also that the paper willspiral open and remain generally around the column of the powder. Whilevarious types of perforations may be used, I find circular holes tobe-eriective where these are of such size as to allow between 10 and 14per inch.

The utilization of explosive cartridges in accordance with the inventionmakes it possible to load them into bore-holes and by comparatively mildtamping thrusts, to cause said cartridge to rupture along the lines ofthe perforations. With my improved cartridge, for example, I have foundthat one firm stroke of the temp is suflicient to secure the explosivein a smooth hole directed upwardly, while about three strokes aresuflicient to give the maximum loading densityf An outstandingadvantageof the improved cartridge of my invention lies in the fact that theminer is no longer obliged to slit the car tridge before tamping thesame. Thus, he avoids spilling powderand actually handling the loosepowder. The time involved in the splitting operation is also saved. Thisbecomes a big factor when a loading of 300 or more cartridges isinvolved. Y

.In describing the invention I have applied it stood that any type ofshell other than paper may be used, provided said material is rupturableunder the conditions outlined. Such materials as regenerated cellulosefilm and various other natural and synthetic materials are applicable,

It is apparent also that the cartridges according to my invention, mayor may not be coated with paraffin or other waterproofing agent. The innous; or semi-gelatinous dynamites. I- find it particularly advantageousin the 'case of the semi-gelatins, and with such explosives, which aremore plastic in nature, two rows ofperforations may be sufijicient. Theinvention is not limited, however, to use with dynamite compositions butmay be applied in the case of cartridges .filled with black powder orany other explosi ve material.

Inshells having a diagonal wrap, that is a wrap in whichthere is adiagonal overlap on the outside of the finished shell so that the edgeof the shell paper spirals me finished shell. it is.

preferred that the row of perforations should not cross this spiraldiagonal edge at the paper. but

shall spiral around the shell in the same general direction as said edge01' the paper. at the same time making an acute angle with the axis ofthe completed cartridge.

shell and in procedure without departure from the spirit of theinvention. I intend to be limited therefore only by the following claim.

I claim:

A substantially cylindrical explosive package 16 comprising an explosivecomposition encased in it rolled shell, said shell being formed from .a-

quadrilateral sheet of rupturable material having at least one set ofparallel opposite sides perpendicular to the longitudinal axis of thefilled cartridge. said sheet being characterized by at least one row ofweakening perforations, said row being so sloped that it meets the saidparallel sides of the shell material at an angle between 45 and 55, saidsheet being rolled into cylindrical form so that the perforations arespirally disposed on and extend substantially from end to end of thefinished shell. a

CLAUDE n BARKER.

